Wood surfaces on furniture and other fine wood products are typically finished with stains, lacquers and other coatings to provide aesthetically pleasing finishes. Furniture finishing of the highest quality traditionally employs finishing protocols using cellulosic lacquers, such as nitrocellulose lacquer. Cellulosic lacquers are relatively inexpensive, easy to apply and repair, and importantly, can be rubbed/buffed to the deep, high quality luster desirable in the fine furniture market. Cellulosic lacquers, however, have several disadvantages, including poor resistance to abrasion and solvent/chemical attack.
Various alternatives to cellulosic lacquers have been developed to improve the durability of wood finishes. Thus cellulosic lacquers have been replaced with thermosetting coatings. Other approaches to obviate the disadvantages of cellulosic lacquers have sought to increase the hardness of cellulosic lacquers by adding cross-linkable functionality to lacquer components and curing the applied finish. These approaches provide wood finishes with greater chemical and abrasion resistance, but do so only with compromise of finish quality and repairability available using traditional cellulosic lacquers.
The present invention provides a novel method for improving the physical characteristics, for example, mar and chemical resistance not only of traditional wood, finishes but other surfaces as well, including, but not limited to, leather, metallic, plastic, textile and painted surfaces. In accordance with one embodiment of this invention, a traditionally finished wood surface is wetted with a free-radical curable polish composition. The surface is wiped free of excess polish leaving an ultra thin, continuous, preferably visibly indiscernible, polish film. The surface is then exposed to free-radical initiating conditions to cure the polish film. The cured, polish-coated surface not only retains the high quality sheen and luster of the underlying finish, but surprisingly, the cured ultra thin coating provides the polished surface with a significantly improved resistance to abrasion, water staining and chemical/solvent attack.
The present invention also provides a novel water extendible free-radical curable polish formulation exhibiting excellent open-time and wipeability. The polish composition is formulated to have surface tension characteristics that allow it to be applied to form stable, ultra-thin films on widely variant surfaces, including traditional wood finishes. The applied films can be polymerized, for example by UV or electron beam radiation, to form a hard, non-tacky, high gloss, high clarity surface. Use of the present polish composition in the end processing step of furniture manufacturer helps to minimize marring of wood surfaces during shipment and thereby reduces costs of labor and materials for refinishing.
In one embodiment of the present invention the curable polish composition comprises an olefin functional polymer or an olefin functional pre-polymer and a silicone or silicone copolymer in a water extendible aqueous emulsion. The present UV curable polish compositions are formulated to include as well one or more photoinitiators, which ingredients are not required for (but can be present in) electron beam (EB) curable polish compositions in accordance with this invention. The present polish composition typically comprises about 90 to about 60% water, and the total polymer solids content of the polish composition ranges from about 10 to about 40% by weight with the ratio of olefin functional polymer or pre-polymer to silicone or silicone copolymer components ranging from about 2:1 to about 1:8 more preferably about 1:1 to about 1:6.
In one preferred embodiment the polish composition of the present invention includes an olefin functional polymer, preferably a polyacrylate, polyvinyl chloride, polycarbonate, polymethacrylate, a polyurethane or a copolymer thereof, a water dispersible silicone or silicone copolymer, a free-radical initiator, a water miscible organic solvent, a water immiscible organic solvent, water, and an emulsifier in an amount effective to stabilize the emulsion. In an alternative embodiment the olefin-functional (radical curable) component of the composition is a poly(olefin functional) monomer or oligomer, preferably in combination with a water dispersible, optionally olefin-functional, polymer.
The polish composition is applied by wetting the substrate surface to be treated in accordance with the invention with the polish composition and wiping the polish-wet surface, preferably with an absorbent pad to remove excess polish composition and provide a thin substantially uniform coating. Thereafter the wiped surface is exposed to free-radical initiating conditions to initiate free-radical propagated polymerization of the applied polish coating.